1. Field of the Invention
The present invention relates to a semiconductor light-emitting device and a method for producing the device.
2. Related Prior Art
Japanese Patent published as JP-H10-242582A has disclosed a method for forming a steep edge, nearly normal to a primary surface of a group III-V compound semiconductor. In this method, an etching mask is formed onto the III-V compound semiconductor, and the mask has an edge, where the vertical edge is to be formed, along a direction perpendicular to the crystal orientation [0-1-1]. However, this method exposed the facet of the active layer during the processing, which may degrade the quality thereof, in particular, various centers or dislocations may be induced.
Another Japanese Patent published as JP-H05-090694A has disclosed a semiconductor laser diode. The process for forming this laser diode includes a formation of a waveguide stripe along a <-1-11> orientation on the p-type InP substrate, whose primary surface is (1-10) surface normal to a {111} surface, and an exposure of a mirrored surface with a crystal orientation of {111} in both sides of the waveguide stripe. Thus, the process may manufacture the laser diode, whose mirrored surface perpendicular to the waveguide can be obtained by the etching without the cleaving of the InP substrate, accordingly, the laser diode shows a relatively threshold current and is capable of integrating with other semiconductor devices.
However, this process prevents to use a semiconductor substrate with (100) surface as the primary surface, which causes the degradation of the quality of the semiconductor layers grown thereon. Moreover, the process is unable to cleave the substrate along the (011) surface, which causes not to obtain a laser diode chip with a rectangular shape.
Still another Japanese Patent published as JP-2001-024276A has disclosed a light-emitting device that does not cause a catastrophic optical damage even in an operating condition of high output power and shows a harder tolerance to a kink level appeared in the I-L characteristic of the light-emitting device. The active layer of this device is formed on the optical guiding layer and except for a region close to the edge thereof. The first cladding layer with the second conduction type is formed onto the active layer. The current blocking layer has an opening formed on this first cladding layer. This opening does not reach the edge of the device. The second cladding layer with the second conduction type is formed at least a portion within the opening.
However, the process to form the light-emitting device above accompanies with the cleavage of the substrate, which may cause not only a scattering of the resonator length but the degradation of the resonator facet.
Japanese Patent published as JP-H04-216688A has disclosed a method for manufacturing the laser diode, in which a window layer, the band gap energy which is greater than the active layer, is grown on the stacked semiconductor layers as the exposed surface of this stacked layers is placed on the susceptor of the growing apparatus or the fixture for fixing the laser bar in a face-to-face arrangement. Subsequent to the growth of the window layer, an extraordinary portion grown on an edge between the facet of the resonator and the back surface opposite to the one the window layer is grown thereon. That is, the window layer is grown on the facet of the resonator after forming the laser bar and extraordinarily grown portions are removed after the formation of the window layer.
However, this method request that, after the formation of the laser bar, the window layer is formed onto the facet of the bar and the extraordinarily grown portion is removed. That is, this process requires at least three process steps, the formation of the laser bar by the mechanical cleavage of the substrate, the formation of the window layer onto the facet of the bar, and the removal of the extraordinarily grown portion of the window layer.